WASHINGTON (AP) — Secretary of State John Kerry said Friday he is not optimistic that Iran’s upcoming election will produce any change in the country’s nuclear ambitions, which the U.S. and others believe are aimed at developing atomic weapons. He also reiterated the long-standing U.S. position that it would be “unacceptable” for Iran to acquire a nuclear weapon.

Kerry’s comments came as the Obama administration again ramped up sanctions against Iran to try to force it to prove that its nuclear intentions are peaceful by cutting off much-needed outside state revenue. The sanctions target Iran’s petrochemicals industry, the largest source of funding for Iran’s nuclear program after oil.

Speaking to reporters at a joint news conference with German Foreign Minister Guido Westerwelle, Kerry said any shift in Iran’s nuclear policy will come from the country’s supreme leader, Ayatollah Ali Khamenei, and not the winner of the June 14 presidential election. Khamenei has final say on all state matters.

“I do not have high expectations that the election is going to change the fundamental calculus of Iran,” Kerry said. “This is not a portfolio that is in the hands of a new president or the president; it’s in the hands of the supreme leader. And the supreme leader ultimately will make that decision, I believe.”

Kerry said the U.S. would continue to pursue a peaceful resolution to the impasse but that time is running out. He said Iran’s persistent defiance of international demands to come clean about its nuclear program makes the world more dangerous. Iran insists its nuclear program is intended for civilian energy production.

“Iran needs to understand that the clock is ticking,” he said, noting that Israel, which sees Iran as a threat to its existence, has not ruled out a unilateral military strike against Iranian nuclear facilities. “Every month it goes by gets more dangerous. And the reality is that Israel will do what it needs to do to defend itself.”

Shortly after Kerry spoke, the departments of State and Treasury unveiled the new sanctions, which also hit companies in the Persian Gulf, Cyprus and elsewhere for helping blacklisted Iranian firms succeed in everything from securing new planes to concealing the origin of banned crude exports.

State Department spokeswoman Jen Psaki said the administration’s action “makes clear the risks involved in helping Iran evade sanctions and reaffirms that the only relief Iran will get from sanctions must come through negotiations.”

“Iran continues to ignore its international nuclear obligations, and the result of these actions has been an unprecedented international sanctions effort aimed at convincing Iran to change its behavior,” she added. “These sanctions today send a stark message that the United States will act resolutely against attempts to circumvent U.S. sanctions. Any business that continues irresponsibly to support Iran’s energy sector or to help facilitate the nation’s efforts to evade U.S. sanctions will face serious consequences.”